电脱氧法制取金属铌的研究

以Nb2O5粉末烧结片为阴极、石墨坩埚为阳极,在CaCl2-NaCl熔盐电解质中对Nb2O5阴极进行电脱氧,以制取金属铌。研究了Nb2O5粉末烧结阴极的制取,以及在熔盐电解质中电脱氧Nb2O5的工艺。研究结果表明,在熔盐电解质中电脱氧是通过熔盐电解质渗透到阴极片孔隙中,使Nb2O5粉末烧结片阴极形成良好的导电体,氧化铌被电离,氧离子通过熔盐电解质传导至石墨阳极坩埚,发生反应并以氧气析出。而阴极本身则发生铌离子还原,形成金属铌。研究表明,电脱氧速度和电脱氧效率与电解质与氧化铌接触面大小和电解温度有关,渗透性好、孔隙度高即接触面大的阴极片和高的电解温度将有较高的电脱氧速度和效率。     

Preparation of A357 Alloy Slurry by Pulsed Magnetic Field Processing

Pulsed magnetic field (PMF) processing was employed for preparing semi-solid A357 alloy slurry in this study. The effects of pouring temperature and vibration power on the microstructure of the primary phase in semi-solid A357 alloy slurry were studied, and some characteristic parameters characterized the morphology and the grain size of the primary ??-Al particles were obtained. The results show that the primary ??-Al particles became finer and rounder with the decrease of pouring temperature and/or the increase of vibration power. However, over a certain vibration power, coarse structures appeared again. The slurry with the primary ??-Al particles of average diameter of approximately 92 ??m and average shape factor of 0.56 can be prepared under the action of a PMF at a vibration power of 250?W with pouring temperature of 903?K (630 °C). It was feasible to use PMF processing to prepare semi-solid alloy slurry because of its strong forced convection within the whole bulk melt.     

3104铝合金熔体中Ca的来源分析及其除钙方法

分析计算了3104铝合金中碱土金属元素Ca的主要来源,确定了保温炉内铝液精炼时所采用的除钠剂、打渣剂和覆盖剂中的Ca是铝熔体Ca含量高的主要原因,认为熔剂精炼不能满足高品质3104罐料对Ca含量的要求,采用以高纯氩气为载体向铝熔体中通入四氯化碳并进行二次精炼是确保熔体中低Na、Ca含量的有效方法。     

电场作用下熔铁与铝碳质水口耐材间的润湿和侵蚀行为

摘要：探究了外加电场作用下铁熔体与水口组成材料间的润湿和侵蚀行为。通过高温电润湿实验可知,在铁熔体和水口组成材料基板间施加电场,促进了铁熔滴与固体基板间的润湿,且在一定电场强度范围内,固 液相间的接触角随着电场强度的增加而减小,固 液相间的润湿性变好。对电润湿后两相界面的微观结构进行了分析,结果表明外加电场促进了铁熔体与水口组成材料间的原子迁移,显著改善固液两相界面间的传质、扩散和溶解等作用。电润湿反应过程中铝碳水口表面经脱碳后产生了孔隙,并且在外加电场作用下铁熔体易于向水口基板内部渗透,导致铁熔体对铝碳水口的侵蚀程度较高纯石墨和氧化铝基板更为严重。     

Wetting and erosion behavior between molten iron and aluminum carbon water nozzle in electric field

The wetting and erosion behavior between the iron melt and the nozzle constituent materials under the action of an external electric field was explored. Through the high temperature electrowetting experiment, it can be seen that the wetting between iron melt and water port substrate is promoted by applying electric field, and the contact angle between solid and liquid phase decreases with the increase of electric field intensity in a certain range, and the wettability between solid and liquid phase becomes better. The microstructure of the two phase interface after electrowetting was analyzed, and the results show that the atom migration between the iron melt and the nozzle constituent material is promoted by the applied electric field, and the mass transfer, diffusion and dissolution between the solid liquid two phase interface are also significantly improved. During the electrowetting reaction process, the surface of the aluminum carbon nozzle is decarburized to generate pores, and the iron melt is easy to penetrate into the nozzle substrate under the action of external electric field, resulting in a higher degree of erosion of aluminum carbon nozzle by iron melt, especially on pure graphite and alumina substrate.     

氧化铝输送设备的小改造与大作用

对净化车间氧化铝输送系统堵塞、净化车间与阳极焙烧之间原料供应纠纷、输送到电解的原料不均匀、载氟氧化铝仓出料管插板阀无法关闭等设备进行了相应得改造。结果表明,改造后,保障了电解铝生产。     

Renal damage in rheumatoid arthritis

Finger skin temperature change during contact with a cold aluminium surface was studied in 20 subjects (10 men and 10 women). Contact pressure (0.1 N, 5.9 N and 9.8 N), contact material mass (large one, mass 3559 g, small one, mass 108 g), surface temperatures (-7 degrees C, 0 degree C, +7 degrees C) and whole body thermal balance were controlled as independent factors. The contact experiments were performed in a small chamber and only the first section of the index finger of the left hand was in contact with the aluminium surface. The results indicated that all the factors studied had significant effects on the contact skin temperature change with time. The study confirmed that a modified Newtonian model with two components can accurately describe the contact skin temperature change with time. The study resulted in three predictive models for critical skin temperature when in contact with cold aluminium. The results indicated that metal surfaces in contact with bare hands should not be below 4 degrees C surface temperature. Lower temperatures require insulating material or the wearing of protective gloves.     

A kinetic model for the vacuum refining of inductively stirred copper melts

An experimental investigation into the removal of impurities (bismuth, lead, arsenic, and antimony) from baths of molten copper (blister, anode and cathode type copper) under vacuum was carried out. A pilot scale vacuum induction melting facility was used for these tests. The effects of (1) vacuum levels of 8.0 to 40.0 Pascals, (2) melt temperatures of 1150 to 1350 °C, (3) melt surface area to volume ratios of 6 to 10 m⁻¹, (4) a water cooled condenser placed within a distance of two centimeters above the melt surface, and finally, (5) different levels of dissolved oxygen and/or sulfur contained in the melt, were studied. Kinetic data were obtained for evaluating the potential of a full scale vacuum melting facility. A mathematical model was also developed for the proper interpretation of the experimental results and for making projections for lower pressure and higher temperature levels. The rate of removal of bismuth and lead increased as the chamber pressure was lowered and the melt temperature increased, while removal of arsenic and antimony was negligible. Neither the melt surface area to volume ratio nor the distance of the condenser to melt surface had any significant effects on the rate constants governing the rate of removal of impurities. The rate of elimination of bismuth and lead over the range of 1150 to 1350 °C and 40.0 to 8.0 Pa followed first order kinetics. Removal rates were largely controlled by mass transport in the gas phase. Formerly Graduate Student at McGill University, Montreal, PQ, Canada     

铝/空气电池用铝阳极的研究

研究了铝／空气电池用铝阳极中添加合金元素的作用,镓,铟,铋,锡能增大阳极的开路电压,镁,铋钪可增大阳极的抗性。以高纯铝为基体制得的两种铝阳极合金Ａ１,Ａ２基本上达到了碱性铝／空气电池的要求。以普通铝为基体制得的铝合金Ａ３作为铝阳极,其电化学性能良好。     

Molecular simulation study of cooperativity in hydrophobic association: clusters of four hydrophobic particles

The multibody contribution to the potential of mean force (PMF) of hydrophobic association of four methane molecules in water was investigated by means of umbrella-sampling molecular dynamics. Two systems were considered: (i). a trigonal pyramid with three methane molecules at contact distance forming a fixed base, the fourth molecule being placed on the top with variable distance from the base; and (ii). a regular uniformly expanding tetrahedron. Methane-methane distances as far as 12.5 A, i.e. beyond the second solvent-separated minimum of the PMF, were considered to address the baseline problem. In contrast to the small effect in the three-body case studied previously (Protein Sci 9 (2000) 1235), the multibody contribution was found to amount to approximately 0.2 kcal/mol per methane-methane pair, or approximately 25% of the depth of the contact minimum in the PMF. The main effect of the multibody contribution to the PMF is a reduction of the height of the barrier between the contact and solvent separated minima and a narrowing of the region of its maximum, while the region of the contact minimum is affected only weakly. The reduction of the barrier is due to four-body contributions. The cooperative contributions to the PMF agree very well with those computed from the molecular surface of the systems under consideration, which further supports earlier observations that the molecular surface can be used with good accuracy to describe the energetics of hydrophobic association.     

Use of waste anode dust for sorption of Ni(II) from aqueous solution

Abstract

This study was aimed at investigating the sorption of Ni(II) ions on anode dust which is an industrial waste material of aluminium production. The effects of various parameters such as the initial pH, contact time, temperature and initial concentration were studied. The thermodynamic parameters were determined. The positive values of enthalpy change ΔH suggested the endothermic nature of the sorption process. The sorption kinetic data could be described well using a pseudo‐second‐order model and the equilibrium data could be fitted well to the Langmuir and Freundlich isotherm. It can be concluded that the obtained sorption capacity for Ni(II) ions is a good indicator of the anode dust potential for use in an aqueous sorption system.

Cette étude avait pour but l’investigation de la sorption des ions de Ni(II) sur la poussière d’anode, un matériau de rejet industriel de la production de l’aluminium. On a étudié l’effet de divers paramètres comme le pH initial, la durée de contact, la température, et la concentration initiale. On a déterminé les paramètres thermodynamiques. Les valeurs positives du changement d’enthalpie ΔH suggéraient la nature endothermique du procédé de sorption. On pourrait bien décrire les données cinétiques de la sorption en utilisant un modèle de pseudo deuxième ordre et l’on pourrait bien ajuster les données d’équilibre à l’isotherme de Langmuir et Freundlich. On peut conclure que la capacité de sorption obtenue pour les ions de Ni(II) est un bon indicateur du potentiel de la poussière d’anode pour utilisation dans un système aqueux de sorption.     

氧化铝输送设备的小改造、大作用

净化车间氧化铝输送系统堵塞、与阳极焙烧有供应纠纷、输送到电解的原料不均匀、载氟氧化铝仓出料管插板阀无法关闭,我们相应进行了设备的小改造,结果证明改造都发挥了大作用,保障了电解铝生产。     

Research on the grain refinement under pulsed magnetic field

In this paper,the principle of Pulsed Magnetic Field(PMF) force was analyzed through mathematical analyses.By theoretical analysis and calculation,the results show that the great electromagnetic force is made in the melt under pulsed magnetic field,as well as changing its direction in different places of melt at the same time.It enforces the crystallizing nucleus and brittle crystallite to fragment in the solidification processing.From the point of view,one of the main factors of grain refinement is that the fragmentations occur under a pulsed magnetic field by preliminary judgement. The feasibility of application in the metallurgical industry under PMF was discussed through comparing the results of grain refinement under EMS.According to the theoretic calculation,the power consumption under EMS is 5 -8 times the amount under PMF,when both of magnetic flux density B are 0.07T.That is to say,the better effect on grain refining can be obtained under PMF,compared with EMS,even in the lower power consumption.The solidification experiments of Sn-20%Pb alloy are conducted under the same experimental conditions that the magnetic intensity is 0.07T in the center of the crucible,it also shows that PMF has a better effect on grain refining than EMS. Combined with the continuous casting process,the influence of pulsed parameters and the metallurgical effects with applying PMF at different solidification stages was investigated.There are different grain refining effects under PMF in different solidification stages,and there are different grain refining effects under PMF in different PMF parameters.For the Sn-20%Pb alloy or silicon steel,it is more effective during the initial stage,in which the pulse frequency is 5Hz.For the Sn-20%Pb alloy,the average grain size ofβphase is the smallest,when applying the PMF during the temperature of melt decreasing from 201℃to 184℃.Further investigation of the specified technique parameters for industrial applications are required.     

Development of an Inert Anode for Electrowinning in Calcium Chloride–Calcium Oxide Melts

Studies were performed investigating the anodic testing of calcium ruthenate for electrowinning in calcium chloride–calcium oxide melts. The results showed that calcium ruthenate may be suitable as an inert anode in calcium chloride containing melts as it exhibited a low rate of corrosion in melts containing a small amount of calcium oxide, capable of producing oxygen on its surface, and did not contaminate the melt. To reduce the amount of ruthenium in the anode, solid solutions of calcium ruthenate in calcium titanate were investigated. At low concentrations, the solid solution is a semiconductor with a relatively low conductivity at room temperature, but at the temperature of operation, 1173 K, the material is an excellent electronic conductor. The other way of reducing the amount of ruthenium is to coat the solid solution onto a substrate. In this way, the substrate would give the mechanical strength while the coating would give the electrical conductivity and corrosion protection. Calcium ruthenate-based anodes can endure long-term use in the laboratory under an applied electrical field with oxygen being liberated on the anode indicating that these materials are candidates for the electrowining in calcium chloride–calcium oxide melts.     

铝电解炭阳极添加氟化铝的形容与应用

本文介绍了阳极糊、预焙阳极炭块中添加氟化铝的实验室研究及工业应用试验，试验结果表明，氟化铝是一种理想的铝用阳极添加剂，它能有效地改善阳极性能，提高阳极的搞氧化能力；提高电流效率、降低直流电耗及吨铝炭耗；降低原铝中硅铁含量，提高原铝质量；增加盈利５０～８０元／ｔ·Ａｌ，有较好的经济效益。     

铝电解用惰性阳极的研究进展

介绍了国内外铝电解惰性阳极方面较有影响的研究工作,探讨了金属、陶瓷和金属陶瓷基惰性阳极选材问题,分析了惰性阳极在研究和应用中出现的一些问题,认为惰性阳极应用于工业生产中还有很长的路要走,希望相关领域的精英参与惰性阳极的研制工作。     

Decarburization of high-chromium melts by argon–oxygen plasma

The treatment of Fe–Cr and Fe–Cr–Ni alloys by means of oxygen-bearing plasma is investigated in the laboratory, using a plasma furnace with a tungsten cathode and a water-cooled copper anode. That permits modeling of the processes in the contact spot of the plasma arc and the melt surface. The mathematical model developed describes the melt–plasma interaction. The kinetic parameters of the decarburization of high-chromium melt by argon–oxygen plasma are determined from experimental data. The results show that considerable decarburization of high-chromium melt is possible, with little loss of chromium, by treatment with plasma containing no more than 15–17% oxygen. Comparison shows that the model data and experimental results are in good agreement.     

NiFe_2O_4基惰性阳极的润湿性及气泡析出行为

利用座滴法和双室透明电解槽对NiFe2O4基惰性阳极的润湿性和气泡析出行为进行研究。结果表明,电解质对NiFe2O4基惰性阳极的润湿性要优于碳素阳极。在低电流密度情况下电解,阳极气泡的析出是一个动态过程,它先在阳极表面形核,以球形方式长大,小气泡在长大过程逐渐汇聚偏移,然后逸出。惰性阳极上析出的气泡尺寸比碳素阳极小,在阳极上的逗留时间也更短。大电流密度情况下,气泡的生成速度加快,尺寸降低,很难准确测量气泡的直径。     

A pilot-scale trial of an improved galvanic deoxidation process for refining molten copper

A laboratory-scale galvanic deoxidation technology developed by earlier workers has been improved, with the aim of developing a prototype pilot-scale deoxidation unit. Each deoxidation cell consists of a one end-closed yttria-stabilized zirconia (YSZ) tube coated with a Ni-YSZ cermet anode on the inner walls. The YSZ tube is immersed, with its closed end in the metallic melt, and an oxygen-chemical-potential gradient across the tube is established by passing a reducing gas through the tube. The melt is then deoxidized by short circuiting it with the anode. Through laboratory experimentation, the nature of the anode/electrolyte interface adhesion was identified to be an important factor in obtaining enhanced deoxidation kinetics. The kinetics of oxygen removal from the melt was increased by an order of magnitude with an improved anode/electrolyte interface. A pilot-scale refining unit consisting of 53 cells with the improved anode/electrolyte interface was manufactured, and a field evaluation of the galvanic deoxidation of copper was conducted. The deoxidation-process model was modified to include multiple deoxidation cells, which were required for the pilot-scale trials, and to analyze the effect of electrolyte/electrode adhesion on deoxidation kinetics. Preliminary studies on process component lifetimes were conducted by investigating the thermal cycling, corrosion behavior of the electrolyte, and stability of the cermet anode structure. Based on the results of the field trial and the analyses of the process component lifetime, future work needed toward commercializing the technology is discussed.     

冷坩埚电磁冶金数值模拟研究

冷坩埚电磁冶金技术是制备特殊新材料的重要技术,其特点为凝壳参数可通过分瓣感应加热和坩埚水冷控温的方法控制。采用数值模拟,从磁通密度和电磁力方面,研究熔融精炼使用的冷坩埚结构和电磁场。研究结果表明：在坩埚强度允许范围内,分瓣数增加有利于提高透磁性能,熔体产生的磁通密度和所受的电磁力主要集中于切缝附近。